Crews had removed a debris boom that was boxing in the dolphin, hoping it would then find its way to sea during high tide.

However, the dolphin was found dead Friday morning.

The FDNY issued the following statement Friday: “Members of Rescue 5, Rescue 2 and the Scuba Unit were in the vicinity for pre-scheduled dive training incorporating new equipment purchased after Sandy when the Department of Environmental Conservation, which was unable to locate the dolphin, came upon it.

“The dolphin was found dead today at approximately 11:30 a.m., and was transported to shore, where it was secured for transport by a Department of Environmental Control (DEC) officer, the Riverhead Foundation said in a statment. Our team has met up with the DEC officer and retrieved the dolphin for a necropsy.”

“Simultaneously, we received a call about another common dolphin that was reported deceased on the beach at Point Lookout, New York. This animal was also recovered by our team. It appears to have died within the last 24 hours. Both dolphins will be assessed for cause of death.”

The creek is a narrow body of water on the northwest side of the island.